This invention was not made with Government support.
The present invention relates to an apparatus which is attached to a liquid-filled pipe for freezing a plug of frozen liquid in the liquid-filled pipe, in order to plug said pipe at a point where there is no conventional valve, so that pipe repairs can be performed downstream of the plug, and then for defrosting the freeze heads and evaporator so that the apparatus can be quickly and easily removed from the frozen pipe without damaging the apparatus.
A pipe freezer works by removing heat quickly enough from the liquid within a section of pipe that an ice plug forms in that section of pipe, thus effectively preventing the flow of liquid through that section of pipe. This ice plug acts as a temporary valve. When the ice plug is properly maintained (kept frozen), repairs can be performed on the pipe in the vicinity of the ice plug without the need to drain the piping system.
A common problem with pipe freezers is that after the freeze operation is complete the freeze heads and the evaporator are frozen to the pipe. This often leads to the operator forcing the freeze heads or evaporator to separate from the pipe causing damage to the pipe freezing equipment.
If one adds enough heat to the evaporators, the ice will melt, freeing the head or evaporator from the pipe. There are a few methods of defrosting the freeze heads and the evaporator. For example one can use a hair dyer, hot water, a heat gun, or flame to defrost the freeze heads and the evaporator. These methods are cumbersome and some are unsafe.
A method of defrosting the freeze heads is to use the hot gas from the system to defrost the freeze heads. This is a common defrost method incorporated within refrigeration systems.
The purpose of the Pipe Freezer with Defrost Cycle is to freeze pipes on which it is desired to make repairs, and then to defrost the freeze heads and evaporators so that the pipe freezer can easily be removed from the frozen pipes.
The present inventor invented U.S. Pat. No. 4,309,875 issued to Arthur Radichio on Jan. 12, 1982 for a Pipe Freezer or the Like, in which a self contained freezing device forms a plug of ice within a pipe section. A refrigeration unit supplies refrigerant to a cradle-like freezer unit within which the section of pipe to be frozen is held in spaced relation to the inner face of the freezer. The space between the underside of the pipe and the inner face of the freezer is filled with water, for example, by spraying. As the water in contact with the cradle-like freezer-unit freezes, it covers the outer surface of the pipe section with an ice jacket. Alternatively, a bag of freezable gel may be substituted for the water spray and placed over the inside face of the freezer; and then the pipe section is placed within the fold of the bag. In the case of either alternative, the refrigerant is maintained inside the freezer, and out of contact with the pipe.
My U.S. Pat. No. 6,286,329 issued on Sep. 11, 2001 to Arthur Radichio for a Pipe Freezer. The pipe freezer uses a multi-cavity adapter having from two to eight cavities to fit standard plumbing pipes in copper, steel and plastic, metric and US standard. The refrigeration evaporator fits into a cylindrical bore in the core of the radial multi-cavity array. The cavities are arrayed around the circumference of the bore. The extrusion that forms the array is of aluminum or the like. Any of the cavities on the adapter body can be lined up with the pipe. When a single adapter is being used, the adapter is positioned on the pipe and secured with a strap having hook and loop fastening material. Then the cartridge evaporator is plugged into the adapter.
This pipe freezer with defrost cycle invention has three embodiments, each of which provides for a defrost cycle in order to defrost the freeze heads and evaporalor after the pipe freezer has been used to create a frozen plug in the pipe it is desired to repair. The first and preferred embodiment uses a novel method to defrost the freeze heads and evaporators after the pipes it is desired to repair have been frozen:
A teeder tube runs within the suction line. This tube serves two purposes: first, during freeze mode, to feed the refrigerant to the evaporators for heat removal from the pipe. And second, during defrost mode, to deliver hot gas to the evaporator for defrost after the pipe freezing operation is complete in this embodiment, for at least a portion of its length the hot gas line is incorporated into the feeder tube.
To achieve this combination of freezing and defrosting the evaporators a common feeder is utilized. The feeder tube will allow very saturated vapor to flow from the metering devices to the evaporators when the system is in the freezing mode. In the hot gas mode (defrost mode) the hot refrigerant gas is diverted away from the condenser by incorporating a tee on the discharge line with an electrically or manually operated valve. When the hot gas is diverted to the feeder tube, it travels into the evaporator adding heat and defrosting the freeze heads and the evaporator. The refrigerant then travels back to the compressor through the suction line.
The best method for defrost is to use a manual on-off switch in conjunction with an electric valve. Other methods may be incorporated, such as including a hand valve, or a timer controlling an electric valve.
Current pipe freezers extend the metering device into the evaporator with the feeder tube. Other types of metering devices can be used in conjunction with the feeder tube such as thermostatic expansion valves, automatic expansion valves, electronic expansion valves, fixed orifice, and capillary tubes.
The second embodiment (nonpreferred) is similar to the preferred embodiment in that the saturated vapor tube runs through the suction line for at least a part of its length, but the hot gas line runs separately from and outside of the suction line, whereas with the preferred embodiment, for at least a part of its length the hot gas line is incorporated into the feeder tube.
The third embodiment (nonpreferred) is similar to the preferred embodiment except that it utilizes a reversing valve to provide different paths for the refrigerant depending upon whether the pipe freezer is in the freeze or defrost cycle.
The above features are objects of this invention. Yet further objects are as follows:
An object of the instant invention is to provide a pipe freezer with a defrost cycle so that the pipe freezer can easily be removed from the pipe to be repaired after a frozen plug has formed in the pipe.
A further object is to provide a pipe freezer with defrost cycle system that is economical in cost to manufacture.
Yet another object is to provide a pipe freezer with defrost cycle system which is light weight enough to be easily transported from place to place.
These and other objects, features, aspects, and advantages of the present invention will become better understood with regard to the following description, appended claims, and accompanying drawings and will be otherwise apparent to those skilled in the art.